Mycobacterium tuberculosis is a pathogenic microbe causing tuberculosis in human, and is Gram-positive bacillus belonging to genus Mycobacterium having acidophilic properties. In spite of the significant decrease of tuberculosis in recent years, it has recently become serious problems due to increased the incidence rate in elderly and the outbreak of the group infection in the young people who are not experienced tuberculous infection.
On the other hand, it is also known that besides Mycobacterium tuberculosis, non-tuberculous Mycobacteria such as Mycobacterium avium, Mycobacterium intracellulare and Mycobacterium kansasii also exhibit pathogenicity for human. Further, it has also become a big problem for non-tuberculous Mycobacteria to develop disease in patients infected with AIDS virus. Since most of these non-tuberculosis Mycobacteriosis exhibit resistance against antituberculous agents, differential diagnosis between tuberculosis and non-tuberculosis mycobacteriosis becomes important for determining therapeutic strategy. However, since differentiation from tuberculosis based on clinical symptom and histopathological observation is quite difficult, the diagnosis has to be determined by using identification of bacteria.
When the differential diagnosis is made between the tuberculosis and the non-tuberculosis mycobacteriosis, the specimens are generally separately cultured in the Ogawa medium, and then subjected to biochemical tests for the identification of the species. However, since growth of genus Mycobacterium is generally slow, a considerable time has to be required for the culture. For that reason, when the conventional fundamental tests such as smear examination and culture examination are conducted, the isolation and culture of bacteria for obtaining the diagnostic result to determine tuberculosis or not requires at least for 3 to 4 weeks, and then a time period of further 2 to 3 weeks has to be required for various tests on identification of species.
Although another method for detecting tubercle bacillus using anti-genus Mycobacterium antigen antibody is known, specificity to tubercle bacillus is deficient due to cross reaction among species of genus Mycobacterium, and as a result, sensitivity is not sufficient.
Recently, a diagnostic technique by applying nucleic acid amplification techniques such as polymerase chain reaction (PCR) has been examined as a useful means, as well as application thereof to the diagnosis of tubercle bacillus. It has been studied whether various regions on DNA genomes of tubercle bacillus can be used as a target for detecting tubercle bacillus using PCR.
For example, a method for detecting genetic region coding the 65 KDa antigen of genus Mycobacterium has been reported (refer to, e.g., non-patent document 1, non-patent document 2, non-patent document 3, non-patent document 4, and non-patent document 5). However, it is known that the same genus such as M. avium, M. fortuitum, M. paratuberculosis, M. kansasii, M. malmoense, BCG and M. marinum as well as Mycobacterium tuberculosis have the gene of the 65 kDa antigen is known. Especially, since the 65 kDa antigen has a high cross reactivity with M. avium or M. kansasii which are the representative causative microorganisms of non-tuberculosis Mycobacteriosis, the method for detecting the gene of 65 kDa antigen has still a problem as a method for specifically detecting Mycobacterium tuberculosis. 
Further, a test examination for identifying M. tuberculosis using a gene sequence coding MPB70 protein, which was identified by DNA of Mycobacterium bovis, has been studied (refer to e.g. non-patent document 6). However, Kulski, et al. reported the result in FEMS Microbiol. Lett. 1997 Mar. 1; 148(1): 43-48 (non-patent document 7). Namely, as a result of an examination by PCR, the cross reaction with the similar sequence in DNA of M. kansasii was found to occur when MPB70 protein was targeted. Consequently, this method has still a problem as a method for specifically detecting Mycobacterium tuberculosis. 
Alternatively, a method for detecting M. tuberculosis/bovis using a gene sequence coding a protein antigen b (Pab) as a marker has been reported (refer to e.g. non-patent document 8), and usefulness of this marker in using for detecting M. tuberculosis/bovis has been confirmed. However, since in the case of Pab gene, only one copy can exist in genome of M. tuberculosis, it is considered not so preferable as a material for targeting nucleic acid amplification (contrary to that, in the case of IS6110 sequence described below, ten copies exist in genome of M. tuberculosis).
Further, RFLP (Restriction fragment length polymerization) by using IS6110 as a probe was reported to be able to utilize for diagnosis of tubercle bacillus (refer to e.g. non-patent document 9). This sequence has widely been used as an important tool for the epidemiological survey of tuberculosis in many countries in the world. IS6110 is an insertion sequence specific to tubercle bacillus, and exists plurally on the chromosomal DNA, with the different number and location depending on the strain, and this genetic character is inherited stably in some extent. Therefore, different RFLP patterns are shown depending on difference in strain, and grouping based on their origins can be possible. There are many reports on detection method of tubercle bacillus using IS6110, indicating sensitivity exceeding 75% as well as specificity of nearly 100%. However, in the mean time, a study result indicating that there is a possibility to cause false positive in the detection method using IS6110, has also been reported (refer to non-patent document 10). Although there is a detection method performing PCR by designing a primer specific to IS6110 has also been known (refer to e.g. patent document 1, patent document 2, patent document 3 and patent document 4), this method has a problem that sequences relating to IS6110 derived from genus Mycobacterium other than M. tuberculosis is amplified, too. Further, IS6110-like sequences exist in other microorganism species other than tubercle bacillus, and as a result, it has been suggested that these microorganisms might be detectable by the detection method of targeting IS6110. Consequently, any of the conventional methods for detecting IS6110 has a problem of insufficiency in specifically detecting Mycobacterium tuberculosis. 
Accordingly, there is a need for establishing a novel method for specifically detecting Mycobacterium tuberculosis.     [Patent Document 1]: JP-A-05-507617    [Patent Document 2]: JP-A-11-514522    [Patent Document 3]: JP No. 2814422    [Patent Document 4]: U.S. Pat. No. 5,370,998    [Patent Document 5]: JP-A-60-500717    [Patent Document 6]: JP-A-60-281    [Patent Document 7]: U.S. Pat. No. 5,210,015    [Patent Document 8]: U.S. Pat. No. 5,538,848    [Patent Document 9]: U.S. Pat. No. 5,801,155    [Patent Document 10]: U.S. Pat. No. 5,925,517    [Patent Document 11]: U.S. Pat. No. 6,492,121    [Patent Document 12]: JP No. 2650159    [Patent Document 13]: JP-B-07-114718    [Patent Document 14]: JP-A-58-040099    [Patent Document 15]: JP-A-62-265999    [Non-patent Document 1]: Chia et al., J. Clin. Microbiol., 1990, 28(9), 1877-1880.    [Non-patent Document 2]: Brisson-Noel et al., Lancet, 1989, 334, 1069-1071    [Non-patent Document 3]: Hackel et al, Molecular and cellular Probes, 1990, 4, 205-210.    [Non-patent Document 4]: Woods, Cole, FEMS Mycrobiology Letters, 1989, 65, 305-310.    [Non-patent Document 5]: Hance et al., Molecular Microbiology, 1989, 3(7), 843-849.    [Non-patent Document 6]: Kulski et al., J. Clin. Microbiol., 1995, 33, 668-674    [Non-patent Document 7]: Kulski et al., FEMS Microbiol. Lett. Mar. 1, 1997, 148(1), 43-48.    [Non-patent Document 8]: Sjobring et al., J. Clin. Microbiol., 1990, 28(10), 2200-2204.    [Non-patent Document 9]: Hermans P W M et al., J. Clin. Microbiol., 1990, 28, 2051-2058.    [Non-patent Document 10]: Lee et al., Neurological Sciences, 1994, 123, 173-179.    [Non-patent document 11]: Thierry et al., Nucleic acid Res., 1990, 18(1), 188.    [Non-patent Document 12]: Nucleic acids Res., 1986, 14, 6115-6128.    [Non-patent Document 13]: Kent P T, Kubica G P, Public Health Mycobacteriology, A Guide for the Level III Laboratory, U.S. Department of Health and Human Services, Public Health Service, Center for Disease Control, Atlanta, U.S.A., 1985, p. 31-55.